From e05f609b61c23846ee21a24a97631d2364f55078 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Fri, 16 Apr 2010 22:58:15 +0000
Subject: [PATCH] Add an autoconf check for -retain-symbols-file and
 conditionalize use of that option with it. This eliminates an imprecise
 "Linux" test, and should help support old versions of gold.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101560 91177308-0d34-0410-b5e6-96231b3b80d8
---
 Makefile.config.in          |  4 ++++
 Makefile.rules              | 13 ++++++-----
 autoconf/configure.ac       |  3 +++
 autoconf/m4/link_options.m4 | 43 +++++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/Makefile.config.in b/Makefile.config.in
index 1b61f0908a8..a3384e7af32 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -337,3 +337,7 @@ ENABLE_LLVMC_DYNAMIC_PLUGINS = 1
 NO_MISSING_FIELD_INITIALIZERS = @NO_MISSING_FIELD_INITIALIZERS@
 # -Wno-variadic-macros
 NO_VARIADIC_MACROS = @NO_VARIADIC_MACROS@
+
+# Flags supported by the linker.
+# bfd ld / gold -retain-symbols-file file
+HAVE_LINK_RETAIN_SYMBOLS_FILE = @HAVE_LINK_RETAIN_SYMBOLS_FILE@
diff --git a/Makefile.rules b/Makefile.rules
index 9ff6c79b6e5..6e177813148 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -561,7 +561,7 @@ ifeq ($(HOST_OS),Darwin)
   # Get "4" out of 10.4 for later pieces in the makefile.
   DARWIN_MAJVERS := $(shell echo $(DARWIN_VERSION)| sed -E 's/10.([0-9]).*/\1/')
 
-  SharedLinkOptions=-Wl,-flat_namespace -Wl,-undefined -Wl,suppress \
+  SharedLinkOptions=-Wl,-flat_namespace -Wl,-undefined,suppress \
                     -dynamiclib
   ifneq ($(ARCH),ARM)
     SharedLinkOptions += -mmacosx-version-min=$(DARWIN_VERSION)
@@ -990,13 +990,12 @@ endif
 # Now add the linker command-line options to use the native export file.
 
 ifeq ($(HOST_OS),Darwin)
-LLVMLibsOptions += -Wl,-exported_symbols_list -Wl,$(NativeExportsFile)
+LLVMLibsOptions += -Wl,-exported_symbols_list,$(NativeExportsFile)
 endif
 
-# This isn't really Linux-specific; it works at least on gold and bfd ld, but
-# there's no convenient way to detect it.
-ifeq ($(HOST_OS),Linux)
-LLVMLibsOptions += -Wl,-retain-symbols-file -Wl,$(NativeExportsFile)
+# gold, bfd ld, etc.
+ifeq ($(HAVE_LINK_RETAIN_SYMBOLS_FILE),1)
+LLVMLibsOptions += -Wl,-retain-symbols-file,$(NativeExportsFile)
 endif
 
 endif
@@ -1297,7 +1296,7 @@ ifeq ($(HOST_OS),Darwin)
 
 # Tiger tools don't support this.
 ifneq ($(DARWIN_MAJVERS),4)
-LD.Flags += -Wl,-exported_symbol -Wl,_main
+LD.Flags += -Wl,-exported_symbol,_main
 endif
 endif
 
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 76083d27485..49a140cdc4a 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1022,6 +1022,9 @@ AC_LINK_USE_R
 dnl Determine whether the linker supports the -export-dynamic option.
 AC_LINK_EXPORT_DYNAMIC
 
+dnl Determine whether the linker supports the -retain-symbols-file option.
+AC_LINK_RETAIN_SYMBOLS_FILE
+
 dnl Check for libtool and the library that has dlopen function (which must come
 dnl before the AC_PROG_LIBTOOL check in order to enable dlopening libraries with
 dnl libtool).
diff --git a/autoconf/m4/link_options.m4 b/autoconf/m4/link_options.m4
index 66036de433d..3442e465674 100644
--- a/autoconf/m4/link_options.m4
+++ b/autoconf/m4/link_options.m4
@@ -39,3 +39,46 @@ if test "$llvm_cv_link_use_export_dynamic" = yes ; then
   fi
 ])
 
+#
+# Determine if the system can handle the -retain-symbols-file option being
+# passed to the linker.
+#
+# This macro is specific to LLVM.
+#
+AC_DEFUN([AC_LINK_RETAIN_SYMBOLS_FILE],
+[AC_CACHE_CHECK([for compiler -Wl,-retain-symbols-file option],
+                [llvm_cv_link_use_retain_symbols_file],
+[ AC_LANG_PUSH([C])
+  oldcflags="$CFLAGS"
+
+  # The following code is from the autoconf manual,
+  # "11.13: Limitations of Usual Tools".
+  # Create a temporary directory $tmp in $TMPDIR (default /tmp).
+  # Use mktemp if possible; otherwise fall back on mkdir,
+  # with $RANDOM to make collisions less likely.
+  : ${TMPDIR=/tmp}
+  {
+    tmp=`
+      (umask 077 && mktemp -d "$TMPDIR/fooXXXXXX") 2>/dev/null
+    ` &&
+    test -n "$tmp" && test -d "$tmp"
+  } || {
+    tmp=$TMPDIR/foo$$-$RANDOM
+    (umask 077 && mkdir "$tmp")
+  } || exit $?
+
+  echo "main" > "$tmp/exports"
+
+  CFLAGS="$CFLAGS -Wl,-retain-symbols-file=$tmp/exports"
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[]],[[int main() { return 0; }]])],
+    [llvm_cv_link_use_retain_symbols_file=yes],[llvm_cv_link_use_retain_symbols_file=no])
+  rm "$tmp/exports"
+  rmdir "$tmp"
+  CFLAGS="$oldcflags"
+  AC_LANG_POP([C])
+])
+if test "$llvm_cv_link_use_retain_symbols_file" = yes ; then
+  AC_SUBST(HAVE_LINK_RETAIN_SYMBOLS_FILE,1)
+  fi
+])
+
-- 
2.34.1